The following processes have been known for producing .alpha., .beta.-unsaturated aldehydes useful as medicaments, flavorings, etc., or as raw materials for their production. ##STR1##
Each of the above processes is problematic. For example, Method No. 1 is environmentally unsuitable because of dimethyl sulfide responsible for the bad smell produced in the reaction. The yield of the Method No.2 is quite low. Method Nos. 3, 4 and 5 involve many reaction steps, require severe reaction conditions or reagents which must be handled with great care, and produce the desired product in low yields.